It is intended to continue the purification and characterization of a neutral glucose-1, 6-P phosphatase of brain and liver. The enzyme has a low Km for its substrate (approximately 4 microns) but its specificity is not known although little inhibition is seen with FDP. Likewise other metals may replace the required Mg 2ion. A mitochondrial form of activity has not been solubilized in good yield and a study of regulatory properties is needed. There is nothing to suggest that the enzyme is not related to phosphoglucomutase, and glucose-1, 6-P2 synthetase and therefore molecular weight determination and evidence for an enzyme serine-PO3 intermediate will be sought. In addition, studies on the stability of hexokinase II will continue.